Financial Information for Operation Segments (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest									$ 67,963,000	$ 40,556,000	$ 58,601,000
Revenues:
Community base rental income									414,170,000	318,851,000	259,351,000
Gross revenue from home sales									8,566,000	6,088,000	6,120,000
Resort base rental income									134,327,000	130,489,000	129,481,000
Brokered resale revenues, net									3,114,000	3,464,000	4,408,000
Right-to-use annual payments									47,662,000	49,122,000	49,831,000
Rental operations revenues									3,300,000	2,500,000	1,900,000
Right-to-use contracts current period, gross									13,433,000	17,856,000	19,496,000
Right-to-use contracts current period, deferred									(6,694,000)	(11,936,000)	(14,856,000)
Utility income and other									64,432,000	53,843,000	48,357,000
Expenses:
Property operating and maintenance									226,952,000	200,623,000	185,786,000
Cost of home sales									9,475,000	5,683,000	5,396,000
Real estate taxes									47,623,000	37,619,000	32,110,000
Home selling expenses									1,411,000	1,589,000	2,078,000
Sales and marketing, gross									10,846,000	11,219,000	12,606,000
Sales and marketing deferred commissions, net									(3,155,000)	(4,789,000)	(5,525,000)
Property management									38,460,000	35,076,000	32,639,000
Total expenses									641,914,000	548,643,000	458,698,000
Rental home income									14,065,000	7,970,000	4,952,000
Total revenues	171,931,000	181,828,000	174,827,000	181,291,000	162,321,000	164,045,000	127,690,000	135,143,000	709,877,000	589,199,000	517,299,000
Rental home operating and maintenance									7,359,000	4,850,000	3,111,000
Property Operations segment
Segment Reporting Information [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest									348,544,000	281,135,000	237,534,000
Revenues:
Community base rental income									414,170,000	318,851,000	259,351,000
Resort base rental income									134,327,000	130,489,000	129,481,000
Right-to-use annual payments									47,662,000	49,122,000	49,831,000
Right-to-use contracts current period, gross									13,433,000	17,856,000	19,496,000
Right-to-use contracts current period, deferred									(6,694,000)	(11,936,000)	(14,856,000)
Utility income and other									64,432,000	53,843,000	48,357,000
Ancillary services revenues, net									1,940,000	2,658,000	3,490,000
Expenses:
Property operating and maintenance									226,952,000	200,623,000	185,786,000
Real estate taxes									47,623,000	37,619,000	32,110,000
Sales and marketing, gross									10,846,000	11,219,000	12,606,000
Sales and marketing deferred commissions, net									(3,155,000)	(4,789,000)	(5,525,000)
Property management									38,460,000	35,076,000	32,639,000
Total expenses									320,726,000	279,748,000	257,616,000
Total revenues									669,270,000	560,883,000	495,150,000
Home Sales and Rentals Operations segment
Segment Reporting Information [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest									5,560,000	2,742,000	1,405,000
Revenues:
Gross revenue from home sales									8,566,000	6,088,000	6,120,000
Brokered resale revenues, net									1,174,000	806,000	918,000
Expenses:
Cost of home sales									9,475,000	5,683,000	5,396,000
Home selling expenses									1,411,000	1,589,000	2,078,000
Total expenses									18,245,000	12,122,000	10,585,000
Rental home income									14,065,000	7,970,000	4,952,000
Total revenues									23,805,000	14,864,000	11,990,000
Rental home operating and maintenance									$ 7,359,000	$ 4,850,000	$ 3,111,000